Employee Benefits - Additional Information (Details) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021 USD ($) retiree shares	Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)	Jan. 01, 2022 USD ($) Employee	Dec. 31, 2018 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Benefits paid, net of participant contributions and direct subsidy receipts		$ 203
Expected future benefit payment, next twelve months, net of direct subsidies		$ 217
Ultimate health care cost trend rate		4.50%
Remaining estimated life of plan participants		8 years
Commingled funds, redemption notice period		180 days
Return on plan assets		$ 422	$ 1,200
Expected return on plan assets		535	593
Difference between the actual and expected returns on pension and post-retirement plan assets		(113)	618
Active health care benefit expenses		309	307	$ 381
Participating employees' contribution to health care plan		$ 120	$ 133	148
Common stock included in the assets of the Defined Contribution Plan (in shares) | shares		10	11
Expenses related to the 401(k) Plan		$ 96	$ 101	113
US
Defined Benefit Plan Disclosure [Line Items]
Pension liability		1,400
Change in Assumptions for Defined Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation		$ 37	(3)	(4)
Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected health care cost trend rate		5.00%
Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected health care cost trend rate		5.75%
Combined Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan		$ (1,147)	(1,656)
Expected future benefits, next twelve months		850
One-time special termination charge		6	21	6
Settlements		383
Benefit obligation		$ 9,678	12,202	12,217		$ 11,594
Short term interest crediting rates		1.50%
Long term interest crediting rates		3.50%
Plan assets		$ 8,531	$ 10,546	$ 10,493		10,033
Expected long-term rate of return on plan assets		5.50%	6.50%	6.50%
Expected long-term rate of return on plan assets before administrative expenses		5.50%
Return on plan assets		$ 422	$ 1,210	$ 1,575
Combined Pension Plan | Forecast
Defined Benefit Plan Disclosure [Line Items]
Expected long-term rate of return on plan assets	6.00%
Combined Pension Plan | New Lumen Pension Plan | Subsequent Event
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation					$ 2,500
Plan assets					$ 2,200
Number of active participants (in employees) | Employee					2,500
Number of other participants (in employees) | Employee					19,000
Combined Pension Plan | Debt Security
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation, percentage		55.00%
Combined Pension Plan | Derivatives
Defined Benefit Plan Disclosure [Line Items]
Plan assets, target allocation, percentage		45.00%
Combined Pension Plan | US
Defined Benefit Plan Disclosure [Line Items]
Number of retirees | retiree		22,600
Combined Pension Plan | Qualified Plan
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan		$ (1,100)	(1,700)
Contributions		0	0
Settlements		383	0	0
Expected return on plan assets		535	593	618
Combined Pension Plan | Nonqualified Plan
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan		(46)	(51)
Benefits paid by company		5	5
Expected future benefits, next twelve months		$ 4
Combined Pension Plan | Level 3 Parent, LLC
Defined Benefit Plan Disclosure [Line Items]
Amortization period of the plan shortfall		7 years
Combined Pension Plan | legacy Level 3
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan		$ (17)	(33)
Post-Retirement Benefit Plans
Defined Benefit Plan Disclosure [Line Items]
Funded (unfunded) status of plan		(2,776)	(3,043)
Contributions		0	0
Benefits paid by company		247	$ 255	$ 300
Expected future benefits, next twelve months		$ 220
Ultimate health care cost trend rate		4.50%	4.50%	4.50%
Benefit obligation		$ 2,781	$ 3,048	$ 3,037		$ 2,977
Plan assets		$ 5	$ 5	$ 13
Expected long-term rate of return on plan assets		4.00%	4.00%	4.00%
Expected return on plan assets		$ 0	$ 1	$ 1
Post-Retirement Benefit Plans | Minimum
Defined Benefit Plan Disclosure [Line Items]
Expected health care cost trend rate		5.00%	5.00%
Post-Retirement Benefit Plans | Maximum
Defined Benefit Plan Disclosure [Line Items]
Expected health care cost trend rate		5.75%	6.25%